1. Field of the Invention
Embodiments of the present invention generally relate to an RF shutter for reducing the amount of deposition occurring below a substrate pedestal.
2. Description of the Related Art
In plasma processing, a substrate may be exposed to a plasma to perform a process on the substrate. Such process may include deposition, etching, ion implantation, and post deposition treatment. In one such plasma deposition process, plasma enhanced chemical vapor deposition (PECVD), an RF bias may be applied to a showerhead to generate a plasma and/or further excite a remotely generated plasma between the showerhead and the substrate support. In plasma deposition processes, deposition may occur within the chamber at all locations exposed to the plasma. A certain amount of deposition on the chamber surfaces is acceptable provided that the material deposited onto the chamber surfaces does not dislodge or flake off and potentially contaminate the substrate. Once a tolerance level of deposition on the chamber surfaces has been reached, the chamber surfaces may be cleaned or replaced to reduce the likelihood of particle flaking.
Flaking may occur due to any number of reasons. One reason for flaking is that too much material has deposited onto a surface and thus, may flake off due to bombardment with ions in the plasma. Another reason for flaking is movement of chamber components. When a component of the chamber is moved, such as a substrate support raising a substrate into a processing position, the movement of the component may jar components having material deposited thereon. The jarring may cause material to flake off of the components. Therefore, there is a need in the art to prevent undesired flaking in a plasma processing chamber.